This invention relates to a rail fastener arrangement for holding a rail onto a support structure while providing a simple and reliable means to allow lateral adjustment of the rail as may be required in gauge adjustment, i.e., moving the rails closer to each other as the rails become worn or the track settles.
Recent track structures have utilized reinforced concrete ties to support the rails. These ties are preformed with a pair of supports, or shoulders, on each side of the tie, the supports being anchored to the concrete and hence unmovable. A resilient clip is disposed under tension between each shoulder and the adjacent tapered base flange of the rail, in order to hold the rail down on the tie. In addition, a spacer, normally composed of non-conductive material, is disposed between the shoulder and the edge of the rail base to locate the rail centrally between the shoulders and to prevent lateral shifting of the rail on the tie. The spacer may also serve as an insulator between the rails and the supporting track structure in cases where the rails are used to conduct electrical signals. A track structure of the foregoing nature is shown, for example in U.S. Pat. No. 3,700,167.
A common feature in railway track systems is the inclusion of some means to adjust the gauge, or the distance between the centers of the rails. New rails wear primarily on their inside surfaces, which, in effect, causes an increase in gauge. Thus, it is desirable to provide a means for laterally shifting the rails toward each other to bring the rails back into proper gauge. When the rails become excessively worn and no further gauge adjustment is possible, it is also desirable to install new rails and return the gauge to standard.
United Kingdom publication No. 2,010,945 A describes gauge adjustment means that is particularly suitable for use with concrete ties having fixed rail anchor points. A gauge adjustment collar fits around each shoulder and has different thickness walls on each side. To effect a rail adjustment, the outer collar is positioned to dispose a thicker wall between the shoulder and the rail, and the inner collar is positioned to dispose a thinner wall between the other shoulder and the other side of the rail. A second collar is disposed over the first to provide height control and proper tension on the resilient clip in the event the rail is shimmed from underneath.
Another type of gauge adjustment system is shown in U.S. Pat. Nos. 4,047,663 and 4,150,791 which comprise a rotatable eccentric in bearing engagement with a plate supporting the rail. Although such arrangement may provide for simple gauge adjustments, numerous modifications and special parts are required in conventional type track structure, and stresses on the eccentric may cause unintentional rotation and loss of gauge.